Something I can never understand is that where the cosmic background radiation spreads?
If I know well, the cosmic background radiation is actually the light of the Big Bang. If it happened exactly in the same time, it must have spread into the theoretic center of the universe. Which would mean that it already reached every parts of it, in case if it happened in the same time with the Big Bang.
It be possible that it spreads to this direction, but universe expands faster. In this case, the radiation approaches but also moves off - just like everything in the universe. But it's possible only if the universe expands faster than the speed of light. Is this possible?
If it would spread to the direction of the "edge" of the universe, we shouldn't be able to know about its existence, because it would never reach us.
Also, these theories are true with an important conclusion: universe has a beginning in time, which means that once upon a time, it started to expand - consequently it must have a size limit. The reason is that universe has 4 dimensions: length, width, height, and time. One of them (time) is not infinite, so none of the others can be infinite.